Automatic water level control



Nov. 18, 1969 H, 0, McBRlDE ETAL 3,478,374

AUTOMATIC WATER LEVEL CONTROL 2 Sheets-Sheet l Filed March 28, 1968 Nov- 18, 1969 H. o. MGBRxDE ET AL 3,478,357

AUTOMATIC WATER LEVEL CONTROL.

2 Sheets-Sheet 2 Filed March 28, 1968 I N VEN TORS United States Patent Office 3,478,374 Patented Nov. 18, 1969 AUTOMATIC WATER LEVEL CONTROL Harold Oren McBride, St. Joseph, and William H.

Gartley, Stevensville, Mich., assignors to Whirlpool Corporation, Benton Harbor, Mich., a corporation of Delaware Filed Mar. 28, 1968, Ser. No. 716,963 Int. Cl. D06f 33/ 02; F16k 21/18 U.S. Cl. 8-158 9 Claims ABSTRACT OF THE DISCLOSURE Method and apparatus for controlling the introduction of washing liquid into a washing machine having an oscillatory agitator which involves employing a sensing zone in proximity to the axis of the agitator, applying a reduced pressure at the sensing zone, and then introducing additional amounts of water into the machine when the Water has been depleted from the sensing zone as a result of an excessive amount of wash being present in comparison to the amount of Washing liquid.

BACKGROUND OF THE INVENTION Field of the invention Description of the prior art There are apparently very few disclosures in the prior art which sense the actual conditions existing during washing of fabrics in the washing machine as a basis for controlling the amount of washing liquid introduced into the tube of the machine. The most pertinent references known to us are U.S. Patents Nos. 3,030,790; 3,065,618; and 3,093,841 all assigned to the same assignee as the present application. These patents deal with a water level control which relies on sensing torque transmitted from the agitator to the tub of the machine through the clothing load as a means for determining when addition of water is necessary. While these devices operate satisfactorily, the present invention provides an entirely different approach to the problem of sensing operating conditions existing during the washing of fabrics and with the use of simplied circuitry.

SUMMARY OF THE INVENTION This invention is based upon observations of the liquid flow patterns developed in an automatic Washing machine having an oscillatory agitator under varying ratios of washing to washing liqui The water level control of the present invention provides the correct amount of water for a clothing load regardless of the type of fabric being laundered or the load size. This insures optimum washing action since agitation of clothing in too little water may damage the fabrics, whereas agitation of fabrics in too much water does not permit proper washing action of fabrics by the agitator.

Our observ-ations have shown that when there is too high a ratio of fabric to washing liquid in the tub, there is an actual depletion of Water from about the immediate vicinity of the agitator shaft because of the blocking of water currents by the excessive amount of fabrics. In accordance with the present invention, we position a sensing zone in the area which is most likely to be depleted of water when this condition arises, and apply a produced pressure to that zone. Consequently, as long as water is continuously withdrawn from the sensing zone, there is an indication that the amount of water present in the machine is adequate for Washing purposes. However, if the amount of water is insufficient in the tub, the sensing zone will sense air and, through suitable responsive devices, this pickup of air in the sensing zone is used as a signal to operate electrical circuitry which introduces additional amounts of water into the tub for more eflicient Washing action.

One of the advantages of the present invention is the fact that hot water is saved lbecause the tub does not ill above the level necessary to launder the clothing properly. This saves the user bothl in terms of water consumption and fuel. Furthermore, the same saving is effected in the use of laundering detergent, since the amount of detergent needed is proportional to the water level. The control of liquid level within the tub of the machine is also based upon a signal whose reliability does not appear to be adversely affected by the size of the load being laundered. In addition, the mechanism for controlling the level of liquid in accordance with the present invention is simple in operation and does not involve the addition of any costly parts to the present structure of an automatic Washing machine.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a view in perspective, and partially broken away illustrating the type of automatic washing machine with which the improvements of the present invention can be used;

FIGURE 2 is a somewhat diagrammatic showing of the washing machine illustrating the flow pattern of washing liquid when no fabrics are present in the machine;

FIGURE 3 is a view similar to FIGURE 2. but illustrating the conditions which exist when a large load of fabrics is present in the basket with an insuicient amount of laundry liquid;

FIGURE 4 is a view similar to FIGURES 2 and 3, but illustrating the flow pattern of the washing liquid when an adequate amount of washing liquid has been added to the load of fabrics;

FIGURE 5 is a somewhat schematic drawing of a washing machine assembly including the improvements of the present invention; and

FIGURE 6 is a circuit diagram for the electrical circuit involved.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIGURE 1, reference numeral 10 indicates generally an automatic washing machine including a cabinet 11 having an access door 12 for loading fabrics to be washed into the machine. The machine has a control panel 13 which carries a plurality of push-button selector switches 14 and a control knob 15 for selecting different washing cycles, dependent upon the nature of the fabrics being washed, and for selecting washing cycles of varying duration, respectively.

Within the cabinet 11 there is a stationary tub 16 and a perforate basket 17 in which the fabrics to be washed are received. Centrally of the basket 17 is an agitator 18 including an agitator column 19 and a plurality of radially disposed vanes 20 extending from a perforate apron 21. A flexible sealing lip 22 extends from the perforate apron 21 to provide a sealing engagement with the basket 17, as will be explained in a succeeding portion of the specification.

Turning now to FIGURE 2, it will be noted that with no fabrics present in the basket 17, oscillation of the agitator 18 causes water currents to be established in a generally toroidal path as illustrated by the arrows 23 in that figure. As the agitator 18 oscillates, its vanes 20 effectively pump water away from the larea next to the agitator barrel 19. When there is a large clothing load 24 present in the machine, as illustrated in FIGURE 3, however, this large load prevents return of water to the area adjacent the barrel 19. Consequently, an air cavity 25 exists immediately adjacent the barrel 19 when the relative amount of fabrics is greater than the amount of washing liquid available.

With the introduction of a suiricient amount of washing liquid, however, as illustrated in FIGURE 4, the fabric load 24 is suspended in a suicient amount of washing liquid and, as the agitator 19 oscillates, water currents are established as indicated by the arrows 26 which continuously circulate liquid `against the agitator barrel 19 and thereby fill up the air cavity 25. In this condition, there is sutlicient water present for ecient washing action and no more water need be added to the tub 16. The sensing of the existence of the air cavity 25 in laccordance with the present invention is used as a means for initiating introduction of additional amounts of liquid into the tub 16.

As shown in FIGURE 5, the agitator 18 is driven by means of a motor 31 through a transmission 32. The motor 31 yalso operates a positive displacement pump 33 which draws laundry liquid Ifrom the bottom of the tub 16 through a conduit 34 and circulates it to the upper portion of the tub through a conduit 35. An electrically actuated valve 36 controls the addition of supplementary water into the tube 16 through an inlet conduit 37 As previously mentioned, the skirt 21 of the agitator 18 carries a flexible sealing lip 22 whose marginal edge engages the bottom wall of the basket 17. This sealing lip effectively creates a sealed cavity 29 between the agitator skirt 21 and the lower wall of the basket 17 except for an opening 38 in the bottom wall of the basket 17 Apertures 28 are provided along the column 19 to sense the presence of liquid or air in proximity to the agitator. There is, for about one-third of its height, uid communication between the apertures 28 and the cavity 29 by virtue of the space that exists between the hollow interior of the column 19 and its drive shaft 30.

A similar resilient sealing lip 39 depends from the bottom wall of the basket 17 land engages the bottom wall of the tub 16. Consequently, any water pumped from the tub 16 by the recirculation pump 33 through conduit 34 must pass through the apertures 28 of the agitator column 19 and through the opening 38 in the bottom wall o-f the basket 17 The lip 21 is sufficiently exible so that it is lifted from engagement with the tub 16 when the basket 17 is subjected to centrifugal speeds during a spin drying operation.

As the laundry liquid is pumped by the pump 33 through the conduit 35, it encounters a restriction 49 existing between the relatively large diameter conduit and a smaller diameter conduit 40 which delivers the recirculated laundry liquid back into the tub 16. The restriction 49 causes a considerable back pressure to be developed at the zone identied at reference numeral 41 in FIGURE 5. A tube 42 transmits the pressure developed at point 41 to a pressure switch 43. A second pressure switch 44 communicates with the tub pressure by means of a tube 45.

Referring next to FIGURE `6, electrical energization for the control circuit is derived from a pair of terminals 46 and 47 connected to a suitable alternating current source. A timer actuated switch 48, when closed at the initiation of the cycle, applies alternating current potential across the control elements. Upon the initial `application of power, the pressure switch 43 is closed and the pressure switch 44 is opened, as illustrated in FIGURE 6.

This energizes the solenoid operated valve 36 and water begins owing into the tub 16 through the inlet conduit 37. When the water in the tub reaches a level of approximately 8 inches or so, pressure switch 44 closes, and the rotor 31 is energized. The rotor 31 drives the agitator 18 in oscillatory fashion through transmission 32 and also operates the positive displacement pump 33, The latter applies suction through conduit 34 to the bottom of the tub 16. If suicient water is present within the tub for the clothing load being laundered, water is present adjacent the barrel 19 of the agitator 18 and `all of the apertures 28 are closed by liquid. Consequently, only water is drawn through the apertures 28, the opening 38, the conduit 34 and into the discharge conduit 35. The restriction at point 49 creates back pressure at point 41 and this pressure is transmitted to the pressure switch 43, whereup pressure switch 43 opens and solenoid 36 is deenergized.

If, however, the fabric load in basket 17 is too large for the quantity of water present, the pumping action of the agitator 18 evacuates the area near the barrel 19 of water. Thus, pump 33 sucks in some air along with liquid which is ultimately pumped to the conduit 35. As the entrapped air reaches the point 41, it relieves the pressure on the diaphragm of the pressure switch 43. Thus, pressure switch 43 closes and additional water is admitted to the basket by energization of the solenoid 36. The addition of water continues until such time as suiiicient water is present in the tub 16 to insure that water is always present adjacent the agitator barrel 19. When this occurs, and air is no longer drawn through the conduit 34, the proper amount of laundry uid will be present in the tub for the clothing load being laundered, and further additions of water are terminated by the reestablishment of the pressure conditions `in the conduit 35 suflicient to open the pressure sensitive switch 43. It should be noted that relatively few apertures 28 need be exposed to air in order to relieve the pressure on the diaphragm of switch 43.

From the foregoing, it will be understood that the liquid control device of the present invention is completely responsive to the actual conditions existing in the tub at the time of washing operation to provide the optimum amount of washing liquid for any given size load. This insures optimum washing action with a saving in hot water and laundering detergent. The mechanism employed is simple in operation and does not involve the `addition of any costly parts to existing automatic washer structures.

It should be evident that various modifications can be made to the described embodiments without departing from the scope of the present invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are dened as follows:

1. The method of controlling the introduction of washing liquid into a washing machine having an oscillatory agitator which comprises oscillating said agitator about a centrally disposed axis, applying a reduced pressure at a sensing zone in proximity to the axis of said agitator, and introducing additional liquid into said machine when the liquid level is reduced in said sensing zone 2. The method of controlling the introduction of washing liquid into a washing machine having an oscillatory agitator which comprises oscillating said agitator about a centrally disposed axis, continuously withdrawing washing liquid from a sensing zone in close proximity to said axis, continuously recirculating withdrawn washing liquid back into said machine, and introducing additional amounts of washing liquid into said machine in response to the drawing of air into said sensing zone.

3. A washing machine comprising a tub, a basket mounted for rotation within said tub, a vaned agitator disposed within said basket, means for oscillating said agitator, means for continuously withdrawing washing liquid from a sensing zone in proximity to the axis of said agitator, pressure sensitive means receiving the Withdrawn liquid, said pressure sensitive means being responsive to the presence of air in the withdrawn liquid, and inlet means controlled by said pressure sensitive means for introducing additional amounts of liquid into said tub upon sensing of said air by said pressure sensitive means.

4. 'Ihe washing machine of claim 3 which also includes a iiexible sealing slip about the vanes positioned to engage said basket and provide `a seal between the agitator skirt and said basket.

5. The 'washing machine of claim 3 which also includes a flexible sealing lip about the periphery of said basket, said lip being positioned to engage the bottom wall of said tub and being suiciently flexible to be lifted from said bottom wall during rotation of said basket at centrifugal speeds.

y6. A washing machine comprising a tub, a basket mounted for rotation within said tub, an agitator mounted within said basket for oscillation `about the rotary axis of said basket, said agitator having radially extending vanes bottomed by a skirt position and having an apertured column, sealing means extending between said skirt portion and said basket, the bottom wall of said basket having an aperture therein, a pump having its inlet side communicating with the space between said tub and the bottom Wall of said basket, a conduit receiving the discharge of said pump, restriction means disposed in said conduit, a pressure sensitive means sensing the pressure at said restriction means, and inlet means controlled by said pressure sensitive means for introducing additional amounts of washing liquid into said tub.

7. The washing machine of claim 6 in which said sealing means includes a flexible lip on said skirt extending into sealing relation with 4the bottom wall of said basket.

8. The washing machine of claim 6 which includes flexible sealing means extending between said basket and said tub to thereby define a cavity into which liquid access occurs only through said aperture in the bottom wall of said basket.

9. The washing machine of claim 8 in which said sealing means is suiciently flexible to be lifted from said tub during rotation of said basket at centrifugal speeds.

References Cited UNITED STATES PATENTS 3,086,836 4/1963 Ohmann 8-158 3,093,841 6/1963 Cobb et al. 8-158 3,316,569 5/1967 Brenner et al. 8-158 WILLIAM I. PRICE, Primary Examiner U.S. Cl. X.R. 

